Heretofore, resin for use in electronic parts is imparted with flame retardancy by a flame retardant according to the intended use and a part for which the resin is used. Known as the flame retardant are bromine-based flame retardants, phosphorus-based flame retardants, inorganic flame retardants, silicone-based flame retardants, and the like. The phosphorus-based flame retardant is kneaded with the resin containing a polymer containing styrene or aromatic polyester frequently used in copying machines and the resin is imparted with flame retardancy of V-2 to V-0 in the UL94 standard for the flame retardancy of resin materials according to the intended use.
On the other hand, a biomass-derived resin obtained from plants has drawn attention from the viewpoint of reducing the consumption amount of petroleum resources, and polylactic acid containing starch, such as corn, as the raw material is known. The biomass-derived resin, whose strength and flame retardancy are improved by an alloy with a petroleum-derived resin or an additive, is practically used for cases of copying machines and the like.
However, for the flame retardant, petroleum-derived resources are still used. Therefore, a development of a flame retardant utilizing renewable resources, such as plants, has been demanded from the above-described viewpoint.
As those obtained from plants among flame retardants which impart flame retardancy to resin, tannin is described in PTL 1 (Japanese Patent Laid-Open No. 2006-77215), potassium hydrogen tartrate is described in PTL 2 (Japanese Patent Laid-Open No. 2002-348575), and phytic acid is described in PTL 3 (Japanese Patent Laid-Open No. 2009-1747).
Known as flame retardant compounds obtained from plants are tannin, potassium hydrogen tartrate, phytic acid, and the like. However, when the compounds are added to the polymer containing styrene or the aromatic polyester, a composition having high flame retardancy cannot be obtained.
This is considered to be because tannin, potassium hydrogen tartrate, and phytic acid are hydrophilic, and therefore have low compatibility with resin.